Video watermarking with fast detection

ABSTRACT

In general, one aspect of the subject matter described in this specification can be embodied in a system that includes a user interface device; and one or more computers operable to interact with the user interface device and to perform operations including: receiving video data; applying a one dimensional watermark pattern to each of multiple one dimensional data lines in the video data to create watermarked video data; receiving the watermarked video data including the multiple one dimensional data lines; combining the one dimensional data lines to form a one dimensional array of numbers; analyzing the one dimensional array of numbers to detect the one dimensional watermark pattern previously applied to each of the one dimensional data lines; and outputting an indication of a match, to trigger further processing with respect to the watermarked video data, when the analyzing indicates the watermark pattern has been detected.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims priority toU.S. patent application Ser. No. 12/202,071, filed Aug. 29, 2008; thedisclosure of the prior application is considered part of (and isincorporated by reference in) the disclosure of this application.

BACKGROUND

The present disclosure relates to applying and detecting electronicwatermarks in video data.

Electronic watermarking involves the embedding of an imperceptible ordifficult to perceive signal into a work. Common types of works includepictures, video, and audio. Works can then be analyzed later todetermine if a watermark is present within that particular work.Watermarking schemes typically balance a number of competing factors. Itis generally desirable to make a watermark as imperceptible to humandetection as possible so that it does not draw the attention of theaudience of the work. This goal is often at odds with the ability todetect watermarks accurately, because imperceptible watermarks aregenerally less differentiated from the original work. Some watermarksare designed to be robust against manipulations that the associated workcan undergo, such as compression, cropping, or distortion. Otherwatermarks are designed to be less robust in the process of making suchwatermarks less perceptible.

SUMMARY

This specification describes technologies relating to applying anddetecting electronic watermarks in video data.

In general, one aspect of the subject matter described in thisspecification can be embodied in a system that includes a user interfacedevice; and one or more computers operable to interact with the userinterface device and to perform operations including: receiving videodata; applying a one dimensional watermark pattern to each of multipleone dimensional data lines in the video data to create watermarked videodata; receiving the watermarked video data including the multiple onedimensional data lines; combining the one dimensional data lines to forma one dimensional array of numbers; analyzing the one dimensional arrayof numbers to detect the one dimensional watermark pattern previouslyapplied to each of the one dimensional data lines; and outputting anindication of a match, to trigger further processing with respect to thewatermarked video data, when the analyzing indicates the watermarkpattern has been detected. Other embodiments of this aspect includecorresponding methods, apparatus, and computer program products.

These and other embodiments can optionally include one or more of thefollowing features. The one or more computers can include a clientcomputing system, including the user interface device, and a servercomputing system operable to interact with the client computing systemthrough a data communication network. The one dimensional watermarkpattern can include a sinusoid watermark pattern, and the applying caninclude applying multiple different sinusoid watermark patterns todifferent frames of the video data. Moreover, the one dimensional datalines can include at least one of horizontal lines, vertical lines,diagonal lines, radial lines, or concentric circles.

The operations can further include generating the one dimensionalwatermark pattern to encode multiple bits of data, and the applying caninclude applying the multi-bit watermark pattern to one dimensional datalines from different frames of the video data, including at least twodata lines from each of the different frames. The applying can include,for each of the one dimensional data lines: producing a one dimensionaldata pattern from a gain factor, the one dimensional watermark pattern,and a perceptual weighting derived from at least a current onedimensional data line of the multiple one dimensional data lines; andcombining the one dimensional data pattern with the current onedimensional data line in the video data.

The watermark pattern can include a sinusoid, and the analyzing caninclude employing a Fourier transform to detect the sinusoid. Theanalyzing can include using a matched filter to detect the watermarkpattern. The one dimensional data lines can include scan lines of thevideo data, and the combining can include adding the scan lines togetherto form the one dimensional array of numbers. Moreover, the scan linescan include scan lines from different frames of the video data.

Particular embodiments of the subject matter described in thisspecification can be implemented to realize one or more of the followingadvantages. Detection of a watermark by a video playback device canprovide support to robust rights management schemes, the association ofmetadata with the video, or the aggregation of viewer demographic data.Watermark detection can be added to a video playback chain using atechnique that need not require a large memory footprint and can satisfystrict processing time requirements in a media player. Fast detection ofwatermarks can result in cost effective filtering of a large amount ofvideo content. The monitoring of broadcast videos can result in theassurance that paid content such as commercial advertisements are beingbroadcast. Computationally efficient detection of watermarks can resultin the implementation of watermark detection on electronic devices withlimited computational ability or battery power, such as mobile computingand phone devices. The size of the watermark pattern can be relativelysmall, since it is one dimensional. Thus, systems employing thesetechniques can readily search for multiple different watermarks, whichcan be fully known and recorded before detection begins since storage ofsmall watermarks can be accomplished with minimal memory requirements.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,aspects, and advantages of the invention will become apparent from thedescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example system employing videowatermarking with fast detection.

FIG. 2A is a flow chart showing an example process of adding a watermarkto video data.

FIG. 2B is a block diagram showing another example process of adding awatermark to video data.

FIG. 2C is a block diagram showing an example video distribution systemused to distribute a watermarked video.

FIG. 2D is a block diagram showing another example video distributionsystem used to distribute a watermarked video.

FIG. 3A is a flow chart showing an example process of detecting awatermark in video data.

FIG. 3B is a block diagram showing another example process of detectinga watermark in video data.

FIG. 3C is a block diagram showing an example video analysis system usedto view a video.

FIG. 3D is a block diagram showing another example video analysis systemused to view a video.

FIG. 4 is a list of video frames showing examples of different onedimensional data lines within each frame.

FIG. 5 is a block diagram showing an example process of embedding anddetecting a watermark in different scan lines of different frames in avideo.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIG. 1 is a block diagram showing an example system (1100) employingvideo watermarking with fast detection. An organization can utilize avideo distribution and monitoring system (1100) to distribute awatermarked video and collect viewership information related to thevideo. The distribution system (1100) can include a multimedia serversystem (1105) and a watermarking server system (1110). The watermarkingserver system (1110) can utilize a shared network (1115) such as theInternet to communicate with remote clients (1120 and 1125). Otherconfigurations of the distribution system (1100) are possible, includingfewer and/or more of each individual element.

In some implementations, the multimedia server system (1100) can containa library of multimedia files including, but not limited to, video filesfor public distribution. The multimedia server system (1105) cancommunicate with the watermarking server system (1110). The watermarkingserver system (1110) can receive video files from the multimedia serversystem (1105) and can embed a watermark into the video file. In someimplementations, the multimedia server system (1105) and the watermarkserver system (1110) can be the same system (e.g., a single server farmor a single server machine).

The watermark server system (1110) can communicate with remote clientsover the shared network (1115). In some implementations, the sharednetwork (1115) can include the Internet, cellular telephone networks,and/or broadcast, cable, or satellite TV networks. In addition, theshared network (1115) can include non-electronic components, such as theUnited States Postal Service, through which videos, e.g., on DigitalVersatile Discs (DVDs), can be distributed.

The remote clients (1120 and 1125) can be a desktop computer (1120) anda mobile phone (1125). Other remote clients (1120 and 1125) can alsoinclude a television, or personal music player capable of displayingvideo. The remote clients (1120 and 1125) can obtain (e.g., request andreceive) videos from the watermarking server system (1110) or from othersources. When such videos are played, the remote clients (1120 and 1125)can verify that a watermark is in the video, and then engage in furtherprocessing based the discovery of the watermark. This can involvereporting the discovery of the watermark to the watermarking serversystem (1110), which can record statistics regarding the videos that arebeing displayed.

In addition, the remote clients (1120 and 1125) can incorporatewatermarks into videos that are created on the respective computers, andcommunicate information regarding such watermarks back to thewatermarking server system (1110). Thus, the watermarking server system(1110) can also record statistics regarding the playing of videos thatare created using individual computers throughout the video distributionand monitoring system (1100).

FIG. 2A is a flow chart showing an example process (2100) of adding awatermark to video data. A video can be received (2105) by a computerthat can embed watermarks in video data. Receiving (2105) a video caninvolve the creation of a video, the addition of a video to a videolibrary, and/or preparing to release copies of a video.

Multiple watermarks can be generated (2110). In some implantations,these watermarks can be created based in part or in whole on the videodata received. In some implementations, additional data can be encodedinto these watermarks. For example, a bit stream can be encoded inchanges in amplitude or frequency between different sinusoid watermarks.In some implementations, a number (comparable to a barcode) can beencoded into one or more watermarks. In other implementations, only asingle bit of information need be encoded into a watermark, where thesingle bit simply indicates that the video at hand has been watermarkedby a given system.

One or more watermarks can be applied (2115) to one or more videoframes. One watermark can be applied to each frame to be watermarked.The same watermark can be applied to more than one frame. More than onewatermark can be applied to the same frame. All frames can have one ormore watermarks applied, or some frames can have no watermark applied.

For example, for an image of size R×C, a watermark pattern of C numberscan be used to form the base pattern, which can be duplicated on all Rrows, typically after some modification. The base pattern can beweighted with an “invisibility function” that seeks to find places inthe image being watermarked where the eye is less sensitive to thepresence of the watermark. The watermark can be added with highamplitude in the places where it is calculated that the eye will be lesssensitive, and can be added with low amplitude in places where the eyeis more sensitive. Note that there are many known techniques relating tohow to form such an invisibility function from an image.

Once the video has been watermarked, the video can then be distributed(2120). In some implementations, video distribution can include the saleof a video or rights to publicly show the video. In someimplementations, video distribution can include uploading of a video toan Internet web page for public viewing. In some implementations, videodistribution can include the renting of the video for private viewing.

FIG. 2B is a block diagram showing an example process (2200) of adding asinusoid watermark (2220) to a frame (2205) of a video. In someimplementations, the frame (2205) can be separated into one or more scanlines (2210) corresponding to rows of data (R0, R1, R2, R3) in theimage, which can be divided into columns (C0, C1, C2, C3). It should benoted that the scan lines (2210) are a stylized image and the size ofthe row-column blocks relative to the video image in the frame (2205) inthe figure are for illustrations purposes only. The row and columnblocks here represent the basic elements of the frame (2205), such aspixels.

The scan lines (2210) can be treated as a two dimensional array (2215).A base pattern of C numbers can be created in light of variousconsiderations, such as minimizing visibility, maximizing robustness totranscoding, and so on. For example, a number of simple sinusoids can bechosen as base patterns. Such sinusoids can vary in frequency fromtwelve to eighteen cycles across the image, which can improve theability of the watermarks to survive transcoding processes unaffected(e.g., without being swamped by large, blank areas of the image, such asblue sky, or being completely eliminated by the transcoding processitself). Note that such sinusoid watermarks can have improvedsurvivability with respect to typical video compression techniques, suchas MPEG (Moving Pictures Experts Group) compression since use ofsinusoid watermarks can concentrate the energy in one frequency bin,which can force the compression algorithm to allocate bits to thatparticular bin, thereby causing the watermark to survive compressionbetter than some other watermarks can. Moreover, other frequencies arealso possible, both in the present sinusoid examples, and other examplewatermarks. For example, the frequencies employed can run from ninety toone hundred and thirty cycles.

In some implementations, each base pattern can consist of only onesinusoid at a time, and these sinusoids can be made orthogonal, sincethat can eliminate any interference between different patterns. Thus,some implementations can employ fourteen different base patterns, atfrequencies 12, 13, . . . 18, plus the arithmetic negative of these,which are also detectable patterns. For implementations that provideincreased allowance for cropping or uncertainty in the width of theimage, the number of patterns employed can be limited to just three oreven two patterns, such as 12, 15, and 18 cycles, or even just 12 and 18cycles because close spatial frequencies can be confused. Forimplementations that tolerate extremes of cropping, the number can belimited to just one frequency and either detect its presence (or that ofits negative) or absence. For implementations that minimize visibilityof a watermark, 90 to 130 cycles can be employed. Thus this techniquecan be tailored to a range of target systems depending on the exactlevel of robustness required by taking a tradeoff between the number ofpatterns and the robustness.

The sinusoid watermark (2220) can be created and converted to a onedimensional array (2225) of weighted values (W0, W1, W2, W3). Awatermark embedder (2230) can embed the one dimensional array (2225)into each row of the two dimensional array (2215). The watermarkembedder (2230) can output a frame (2235) of video with the sinusoidwatermark (2220) embedded.

FIG. 2C is a block diagram showing an example video distribution system(2300) used to distribute a watermarked video (2305). The video (2305)can be examined by a watermark generator (2310). The watermark generator(2310) can create a sinusoid watermark (2320) using a sinusoid functiongenerator (2315) and the video (2305) data. In some implementations, thenumber of cycles in the sinusoid watermark (2320) can be optimized forthe expected use of the watermark. In some implementations, the sinusoidwatermark (2320) can include a number of cycles ranging from twelve toeighteen. In some implementations, the sinusoid watermark (2320) caninclude only a single cycle.

A watermark embedder (2340) can embed the sinusoid watermark (2320) intoeach scan line (2325) of the video (2305). The watermark embedder (2340)can use a gain factor (2335) and a perceptual weight (2330) to calculatea one dimensional data pattern for each scan line (2325). The perceptualweight (2330) can be calculated at each pixel in each scan line (2325)by a perceptual weighter (2365), which can take each video (2305) frameas input and produce perceptual weights (2330) as output that are inturn factored into the watermark (2320) before it is added to thatframe's image. Thus, for an image I(R,C), the watermarked image I′(R,C)can be given by I(R,C)+G·P(C)·W(R,C), where G is the gain factor (2335),P is the base watermark pattern, and W is the perceptual weight (2330),which can be computed from a model of the human visual system. Somemodels suggest that human vision does not see blue light very well, thusW(R,C) can be determined based on the amount s5 of blue in a pixel.Moreover, more of the watermark can be embedded into the blue channel,as opposed to the red or green channels. Some models also suggest thatmore information can be hidden in areas of higher spatial frequenciesthan in lower spatial frequencies, and thus higher frequencies can beselected as well.

The video (2305) can be stored in a media storage (2345). The Internet(2350) can provide a remote computer (2355) with access to the mediastorage (2345). In some implementations, some or all of the componentsin the system (2300) can be computer software components such asprograms, daemons, services, or data files. In some implementations,some or all of the components in the system (2300) can be computerhardware components such as hard disks, network cables,applications-specific integrated circuits or general purposemicroprocessors. Moreover, the components in the system (2300) need notbe separated as shown; for example, the sinusoid function generator(2315) can be integrated into the watermark generator (2310).

FIG. 2D is a block diagram showing an example video distribution system(2400) used to distribute a watermarked video (2405) that has associatedmetadata. In some implementations, the video (2405) can be requested.The video (2405) can have associated metadata stored in a video metadatadatabase (2460). A watermark generator (2410) can create a barcode-typewatermark (2420) using a barcode creator (2415). The barcode creator(2415) can associate the barcode-type watermark (2420) with an entry inthe video metadata database (2460), and the metadata can be related tothe video (2405).

A watermark embedder (2440) can embed the barcode-type watermark (2420)into each scan line (2425) of the video (2405). The watermark embedder(2440) can use a gain factor (2435) and a perceptual weight (2430) tocalculate a one dimensional data pattern for each scan line (2425). Theperceptual weight (2430) can be calculated at each pixel in each scanline (2425) by a perceptual weighter (2365), such as described above.

The video (2405) can be stored in a media storage (2445). The Internet(2450) can provide a remote computer (2455) access to the media storage(2445). In some implementations, some or all of the components in thesystem (2400) can be computer software components such as programs,daemons, services, or data files. In some implementations, some or allof the components in the system (2400) can be computer hardwarecomponents such as hard disks, network cables, application-specificintegrated circuits or general purpose microprocessors. Moreover, thecomponents in the system (2400) need not be separated as shown; forexample, the barcode creator (2415) can be integrated into the watermarkgenerator (2410).

FIG. 3A is a flow chart showing an example process (3100) of detecting awatermark in video data. In some implementations, a video can bereceived (3105) by a computer that can detect watermarks. In someimplementations, in addition to receiving the video, the process (3100)can also involve displaying the video, adding the video to a videolibrary, and testing the video to ensure that a watermark was correctlyapplied.

A two dimensional array can be created (3110) from a frame of the video.In some implementations, this two dimensional array can contain thepixel value with the location of the pixel corresponding to the locationof the pixel value. In some implementations, this two dimensional arraycan contain information related to brightness, tone, or otherinformation from the video received.

Data in the two dimensional array can be combined (3115) into a onedimensional array. In some implementations, this combining can involvecalculating the sum or average of values in a row or column, as well asother operations, such as shifting (e.g., shift the pattern by onecolumn on each successive scan line). In some implementations, thiscombining can involve multiple groups of random or periodic samples fromthe two dimensional array. In some implementations, this combining caninvolve the aggregation of multiple collections of data from the twodimensional array. Moreover, sums along diagonals can be used as well.

A determination (3120) can be made of the watermark's presence orabsence. In some implementations, this can include a distinct positiveor negative determination. In some implementations, this can include aconfidence rating indicating how likely or unlikely it has beendetermined that a watermark is present or absent. If a watermark isdetected (3125), further processing (3130) can be performed on thevideo. In some implementations, this processing can include collectingmetadata related to the video, updating a viewership database, and/orvideo editing.

If a watermark was not detected (3125), further processing (3135) can beperformed on the video, or not performed, depending on theimplementation. It will be appreciated that in some implementations,further processing (3130) of a video found to have a watermark can bepartially the same as further processing (3135) of a video found not tohave a watermark. In some implementations, both sets of processing (3130and 3135) operations can relate to viewership or ratings collection,matching metadata to a video, parental control schemes, displayingadvertising information and/or machine control of a device that candisplay the video.

FIG. 3B is a block diagram showing an example process (3200) ofdetecting a one dimensional watermark (3235) in a frame (3205) of avideo. In some implementations, the frame (3205) can be separated by oneor more scan lines (3210). The scan lines (3210) can be divided intorows and columns, such as described above in connection with FIG. 2B.

The scan lines (3210) can be treated as a two dimensional array (3215).The two dimensional array (3215) can be combined into a one dimensionalarray (3220). The one dimensional array (3220) can be examined by awatermark detector (3225) using a matched filter (3230) to determine ifthe sinusoid watermark (3235) is present in the frame (3205). Note thatunlike a traditional two dimensional linear filter, the matched filter(3230) need not employ a number of multiply-add operations on the orderof R×C×N to calculate the matched filter response for an entire image,where R is the number of rows in the image, C is the number of columnsin the image, and N is the number of points in the impulse response ofthe matched filter. This is because the pattern of the present watermarkis one dimensional, rather than two dimensional. Thus, detection can beperformed by first summing over all the columns to produce an array of Cnumbers, and then the amount of computation used to detect the watermarkcan be reduced to C×(R+N), which is typically much smaller than R×C×N.

FIG. 3C is a block diagram showing an example video analysis system(3300) used to view a video (3305). In some implementations, the video(3305) can be examined to determine if it contains a sinusoid watermark(3325). A watermark detector (3310) can analyze the video (3305) using amatched filter (3315). In some implementations, the matched filter(3315) can include a Fourier transformer or an element capable ofperforming a Fourier transformation. Note that employing a Fouriertransform to detect a sinusoid watermark can provide significantadvantages when dealing with video image that have been cropped sincethe Fourier transform can still identify the sinusoid even if the peakof the sinusoid isn't in the expected place, without requiring a trialand error approach to watermark detection. Moreover, the Fouriertransform can provide significant speed advantages in watermarkdetection.

The presence of the sinusoid watermark (3325) can be detected by thewatermark detector (3310). The watermark (3325) can be passed to a videoplayback system (3330). Video playback system (3330) can record thewatermark (3325) and communicate with a viewership data server (3340)over the Internet (3335) to report viewership statistic information.

In some implementations, some or all of the components in the system(3300) can be computer software components such as programs, daemons,services, or data files. In some implementations, some or all of thecomponents in the system (3300) can be computer hardware components suchas hard disks, network cables, applications-specific integrated circuitsor general purpose microprocessors. Moreover, the components in thesystem (3300) need not be separated as shown; for example, the matchedfilter (3315) can be integrated into the watermark detector (3310),which can be integrated into the video playback system (3330).

FIG. 3D is a block diagram showing an example video analysis system(3400) used to view a video (3405) that can have associated metadata. Insome implementations, the video (3405) can be examined to determine ifit contains a barcode-type watermark (3425). A watermark detector (3410)can analyze the video (3405) using a matched filter (3415). The presenceof the barcode-type watermark (3425) can be detected by the watermarkdetector (3410). The barcode-type watermark (3425) can be passed to avideo playback (3430) system. The video playback (3430) can performfurther processing on video (3405).

The video playback (3430) can communicate with a video metadata database(3440) over the Internet (3435) and use the barcode-type watermark(3425) to look up any metadata associated with the video. The metadatacan then be displayed with the video (3405) by the video playback(3430).

In some implementations, some or all of the components in the system(3400) can be computer software components such as programs, daemons,services, or data files. In some implementations, some or all of thecomponents in the system (3400) can be computer hardware components suchas hard disks, network cables, applications-specific integrated circuitsor general purpose microprocessors. Moreover, the components in thesystem (3400) need not be separated as shown; for example, the matchedfilter (3415) can be integrated into the watermark detector (3410),which can be integrated into the video playback system (3430).

FIG. 4 is a list of video frames showing examples of different onedimensional data lines within each frame. A single frame of a video canbe divided in multiple ways (4100) to identify one dimensional datalines for watermark encoding. In some implementations, horizontal datalines (4105) can be used to encode a watermark. In some implementations,vertical data lines (4110) can be used to encode a watermark. In someimplementations, diagonal data lines (4115) can be used to encode awatermark. In some implementations, radial data lines (4120) can be usedto encode a watermark. In some implementations, concentrically circulardata lines (4125) can be used to encode a watermark. Note that theradial data lines (4120) and concentrically circular data lines (4125)implementations can facilitate the use of these techniques with videodata that may be rotated. Moreover, more than one of these differenttypes of data lines can be used within the same video, including withinthe same frame of the video.

It should be noted that the data lines are one dimensional in that eachencoding of a watermark is spread across only a single dimension withina video frame, rather than across the entire two dimensional surface ofthe video frame. This is true even if that single dimension is curvedwithin the two dimensional space, as is the case with the concentricallycircular data lines (4125).

FIG. 5 is a block diagram showing an example process (5100) of embeddingand detecting a watermark in different scan lines of different frames ina video. A watermarking system can embed the same watermark on onedimensional data lines in different frames of a video (5115). Thus, thesame one dimensional watermark pattern can be applied to scan lines thatspan multiple frames. In some implementations, one or more bits of data(5105) can be used to create a sinusoid watermark (5110). The sinusoidwatermark (5110) can be embedded into different one dimensional datalines of different frames of the video (5115).

When examining different frames of the video (5115), a two dimensionalarray (5120) can be constructed using different one dimensional datalines of different frames of the video (5115). The two dimensional array(5120) can be combined into a one dimensional array (5125), which can beexamined to determine if a watermark is present in the video. Moreover,multiple different sinusoid watermarks (5110) can be applied to thevideo (5115) within a given frame, to different frames, or both.

In some implementations, a watermark can be embedded into a portion ofthe video frame image. A video frame can be divided into quadrants ordifferent regions, and each quadrant or region can have a differentwatermark applied therein. Various tiles (e.g., hexagonal tiles), orvertical, horizontal, and/or diagonal stripes can be used. Moreover, insome implementations, the regions to be watermarked can be selectedbased on the image, including an analysis of what portions of the imageconstitute good places to hide the watermark(s), such as described infurther detail above.

Embodiments of the subject matter and the functional operationsdescribed in this specification can be implemented in digital electroniccircuitry, or in computer software, firmware, or hardware, including thestructures disclosed in this specification and their structuralequivalents, or in combinations of one or more of them. Embodiments ofthe subject matter described in this specification can be implemented asone or more computer program products, i.e., one or more modules ofcomputer program instructions tangibly encoded on a computer-readablemedium for execution by, or to control the operation of, data processingapparatus. The computer-readable medium can be a machine-readablestorage device, a machine-readable storage substrate, a memory device,or a combination of one or more of them. The term “data processingapparatus” encompasses all apparatus, devices, and machines forprocessing data, including by way of example a programmable processor, acomputer, or multiple processors or computers. The apparatus caninclude, in addition to hardware, code that creates an executionenvironment for the computer program in question, e.g., code thatconstitutes processor firmware, a protocol stack, a database managementsystem, an operating system, or a combination of one or more of them.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub-programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application-specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto-optical disks, or optical disks. However, a computerneed not have such devices. Moreover, a computer can be embedded inanother device, e.g., a mobile telephone, a personal digital assistant(PDA), a mobile audio player, a Global Positioning System (GPS)receiver, to name just a few. Computer-readable media suitable forstoring computer program instructions and data include all forms ofnon-volatile memory, media and memory devices, including by way ofexample semiconductor memory devices, e.g., EPROM, EEPROM, and flashmemory devices: magnetic disks, e.g., internal hard disks or removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,special purpose logic circuitry.

To provide for interaction with a user, embodiments of the subjectmatter described in this specification can be implemented on a computerhaving a display device, e.g., a CRT (cathode ray tube) or LCD (liquidcrystal display) monitor, for displaying information to the user and akeyboard and a pointing device, e.g., a mouse or a trackball, by whichthe user can provide input to the computer. Other kinds of devices canbe used to provide for interaction with a user as well; for example,feedback provided to the user can be any form of sensory feedback, e.g.,visual feedback, auditory feedback, or tactile feedback; and input fromthe user can be received in any form, including acoustic, speech, ortactile input.

Embodiments of the subject matter described in this specification can beimplemented in a computing system that includes a back-end component,e.g., as a data server, or that includes a middleware component, e.g.,an application server, or that includes a front-end component, e.g., aclient computer having a graphical user interface or a Web browserthrough which a user can interact with an implementation of the subjectmatter described in this specification, or any combination of one ormore such back-end, middleware, or front-end components. The componentsof the system can be interconnected by any form or medium of digitaldata communication, e.g., a communication network. Examples ofcommunication networks include a local area network (“LAN”) and a widearea network (“WAN”), e.g., the Internet.

The computing system can include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the invention or of what may beclaimed, but rather as descriptions of features specific to particularembodiments of the invention. Certain features that are described inthis specification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable subcombination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular embodiments of the invention have been described. Otherembodiments are within the scope of the following claims. For example,the actions recited in the claims can be performed in a different orderand still achieve desirable results. Moreover, the systems andtechniques described herein can be employed with still images ratherthan with video data.

What is claimed is:
 1. A computer-implemented method comprising:receiving video data comprising multiple one dimensional data lines;combining the one dimensional data lines to form a one dimensional arrayof numbers; analyzing the one dimensional array of numbers to detect awatermark pattern previously applied to each of the one dimensional datalines; and outputting an indication of a match, to trigger furtherprocessing with respect to the video data, when the analyzing indicatesthe watermark pattern has been detected.
 2. The method of claim 1,wherein the watermark pattern comprises a sinusoid.
 3. The method ofclaim 2, wherein the analyzing comprises using a matched filter todetect the watermark pattern.
 4. The method of claim 3, wherein theanalyzing comprises employing a Fourier transform to detect thesinusoid.
 5. The method of claim 1, wherein the one dimensional datalines comprise scan lines of the video data, and the combining comprisesadding the scan lines together to form the one dimensional array ofnumbers.
 6. The method of claim 5, wherein the scan lines comprise scanlines from different frames of the video data.
 7. One or morecomputer-readable storage devices comprising processor-executableinstructions that, responsive to execution by a processor, cause acomputer system to implement operations comprising: receiving video datacomprising multiple one dimensional data lines; combining the onedimensional data lines to form a one dimensional array of numbers;analyzing the one dimensional array of numbers to detect a watermarkpattern previously applied to each of the one dimensional data lines;and outputting an indication of a match, to trigger further processingwith respect to the video data, when the analyzing indicates thewatermark pattern has been detected.
 8. The one or morecomputer-readable storage devices of claim 7, wherein the watermarkpattern comprises a sinusoid.
 9. The one or more computer-readablestorage devices of claim 8, wherein the analyzing comprises using amatched filter to detect the watermark pattern.
 10. The one or morecomputer-readable storage devices of claim 9, wherein the analyzingcomprises employing a Fourier transform to detect the sinusoid.
 11. Theone or more computer-readable storage devices of claim 7, wherein theone dimensional data lines comprise scan lines of the video data, andthe combining comprises adding the scan lines together to form the onedimensional array of numbers.
 12. The one or more computer-readablestorage devices of claim 11, wherein the scan lines comprise scan linesfrom different frames of the video data.
 13. A system comprising: a userinterface device; and one or more computers operable to interact withthe user interface device and to perform operations comprising:receiving video data comprising multiple one dimensional data lines;combining the one dimensional data lines to form a one dimensional arrayof numbers; analyzing the one dimensional array of numbers to detect awatermark pattern previously applied to each of the one dimensional datalines; and outputting an indication of a match, to trigger furtherprocessing with respect to the video data, when the analyzing indicatesthe watermark pattern has been detected.
 14. The system of claim 13,wherein the watermark pattern comprises a sinusoid, the analyzingcomprises using a matched filter to detect the watermark pattern, andthe matched filter employs a Fourier transform to detect the sinusoid.15. The system of claim 13, wherein the one dimensional data linescomprise scan lines of the video data, and the combining comprisesadding the scan lines together to form the one dimensional array ofnumbers.
 16. The system of claim 15, wherein the scan lines comprisescan lines from different frames of the video data.
 17. A systemcomprising: a user interface device; and one or more computers operableto interact with the user interface device and to perform operationscomprising: receiving video data comprising video scan lines; combiningat least two of the video scan lines to form a one dimensional array ofnumbers; analyzing the one dimensional array of numbers to detect awatermark pattern previously applied to each of the at least two of thevideo scan lines; and outputting an indication of a match, to triggerfurther processing with respect to the video data, when the analyzingindicates the watermark pattern has been detected.
 18. The system ofclaim 17, wherein the combining comprises adding the at least two of thevideo scan lines together to form the one dimensional array of numbers.19. The system of claim 17, wherein the combining comprises combiningvideo scan lines from different frames of the video data, including atleast two video scan lines from each of the different frames, to detectmultiple bits of data encoded in the watermark pattern.
 20. The systemof claim 17, wherein the watermark pattern is previously applied byusing a gain factor and a perceptual weighting to calculate a onedimensional data pattern for each scan line.